Earnings (Loss) per Share: (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Earnings (Loss) per Share:
Income (loss) from continuing operations	$ (20,825)	$ (219,727)	$ 518	$ 1,279	$ 5,848	$ (2,697)	$ 10,498	$ 12,888	$ (238,755)	$ 26,537	$ 45,302
Less net income (loss) allocated to participating unvested share awards										(79)	(338)
Income (loss) from continuing operations attributable to common shares									$ (238,755)	$ 26,458	$ 44,964
Weighted average common shares outstanding - basic									27,477	27,516	27,226
Dilutive stock options, RSUs and warrants (in shares)										244	344
Weighted average common shares outstanding - diluted									27,477	27,760	27,570
Basic net income (loss) per common share:
Continuing (in dollars per share)	$ (0.75)	$ (7.96)	$ 0.02	$ 0.05	$ 0.21	$ (0.10)	$ 0.38	$ 0.46	$ (8.69)	$ 0.96	$ 1.65
Discontinued (in dollars per share)			$ (0.03)	$ (0.01)	$ (0.05)		$ (0.01)	$ (0.01)	$ (0.04)	$ (0.07)	$ (0.13)
Total (in dollars per share)	$ (0.75)	$ (7.96)	$ (0.01)	$ 0.04	$ 0.16	$ (0.10)	$ 0.37	$ 0.45	$ (8.73)	$ 0.89	$ 1.52
Diluted net income (loss) per common share:
Continuing (in dollars per share)	$ (0.75)	$ (7.96)	$ 0.02	$ 0.05	$ 0.21	$ (0.10)	$ 0.38	$ 0.46	$ (8.69)	$ 0.95	$ 1.63
Discontinued (in dollars per share)			$ (0.03)	$ (0.01)	$ (0.05)		$ (0.01)	$ (0.01)	$ (0.04)	$ (0.07)	$ (0.13)
Total (in dollars per share)	$ (0.75)	$ (7.96)	$ (0.01)	$ 0.04	$ 0.16	$ (0.10)	$ 0.37	$ 0.45	$ (8.73)	$ 0.88	$ 1.50
Antidilutive securities not included:
Stock options, warrants and RSUs (in shares)									2,716	1,818	556